Abstract: Techniques for executing client processes on window servers are disclosed. The techniques allow a client process requiring one or more window extensions to run on a local window server without requiring the local server to support the one or more window extensions. The one or more window extensions can be supported by a remote window server. Accordingly, client processes are able to execute on computer systems that do not locally support the window server or window server extensions, which are required by the client processes.

Abstract: A method and apparatus for exploiting the power of existing device independent graphics and text manipulations, while providing a high level of client-side performance for interactive applications using an object oriented client-side library of constructs. The client-side constructs are analogous to the constructs of a selected server-side imaging model, so that the power and performance of existing imaging models (for example, constructs of the PostScript language) are exploited. In an exemplary embodiment, the client-side constructs are provided for use with the C++ programming language. By establishing a client-side object model using a library of constructs analogous to server-side imaging model constructs, program execution speed and efficiency can be improved without sacrificing the device independence of the imaging model. Using a common base class (i.e.

Abstract: A technique based on synthetic aperture radar (SAR) interferometry is used to measure very small (1 cm or less) surface deformations with good resolution (10 m) over large areas (50 km). It can be used for accurate measurements of many geophysical phenomena, including swelling and buckling in fault zones, residual, vertical and lateral displacements from seismic events and prevolcanic swelling. Two SAR images are made of a scene by two spaced antennas and a difference interferogram of the scene is made. After unwrapping phases of pixels of the difference interferogram, surface motion or deformation changes of the surface are observed. A second interferogram of the same scene is made from a different pair of images, at least one of which is made after some elapsed time. The second interferogram is then compared with the first interferogram to detect changes in line of sight position of pixels.

Abstract: By using two SAR antennas spaced a known distance, B, and oriented at substantially the same look angle to illuminate the same target area, pixel data from the two antennas may be compared in phase to determine a difference .DELTA..phi. from which a slant angle .theta. is determined for each pixel point from an equation .DELTA..phi.=(2.pi.B/.lambda.)sin(.theta.-.alpha.), where .lambda. is the radar wavelength and .alpha. is the roll angle of the aircraft. The height, h, of each pixel point from the aircraft is determined from the equation h=R cos .theta., and from the known altitude, a, of the aircraft above sea level, the altitude (elevation), a', of each point is determined from the difference a-h. This elevation data may be displayed with the SAR image by, for example, quantizing the elevation at increments of 100 feet starting at sea level, and color coding pixels of the same quantized elevation.

Abstract: A carrying sled capable of conversion into a beach umbrella. The carrying sled includes a rigid dish-shaped member with wheels or rails on the dish convex surface. An annular flexible material is secured to and along the outer edge of the dish and includes a draw string positioned around and secured in the outer edge of the flexible material for drawing up the flexible material when desired. Pockets are formed at the outer edges of the flexible material for receiving a spoke disposable therein and passing through a tunnel member on the convex side of the dish for maintaining the flexible material in an outwardly extending position from the edge of the dish. A pole member is secured to the center portion of the concave side of the dish, at the pole either being of the telescoping type or formed by plural interconnecting pole members. In the case of the latter, the remaining ones of the interconnectable members are secured to the concave side of the dish when not in use.

Abstract: A synthetic aperture radar (SAR) target simulator for simulating the radar return, or echo, from a target seen by a SAR antenna mounted on a platform moving with respect to the target includes a first-in first-out memory (26) which has digital information clocked in at a rate related to the frequency of a transmitted radar signal and digital information clocked out with a fixed delay defining range between the SAR and the simulated target, and at a rate related to the frequency of the return signal. An rf input signal having a frequency similar to that utilized by a synthetic aperture array radar is mixed with a local oscillator (16) signal to provide a first baseband signal having a frequency considerably lower than that of the rf input signal. The first baseband signal is converted to a plurality of digital words which are clocked into the memory (26) at a rate related to the frequency of the local oscillator (16).

Abstract: An IGFET push-pull driver circuit includes an output stage having pull-up and pull-down IGFETs for driving an output node. An inverter stage drives the gate of the pull-up IGFET. A current sensing IGFET biased to represent a resistance is coupled between the pull-up IGFET and the output node to provide a voltage drop which is proportional to the current flowing through the pull-up IGFET. A regulating IGFET with its channel coupled between the gate of the pull-up IGFET and the output node and with its gate coupled to the juncture of the pull-up IGFET and the current sensing IGFET, responds to the voltage drop across the current sensing IGFET to provide feedback control of the conductance of the pull-up IGFET. The maximum output current of the driver is limited to a value which remains substantially constant over a wide range of processing parameters, operating temperature and load impedance.

Abstract: Apparatus for demodulation and correlation of a code modulated 10 MHz signal is comprised of a sample and hold analog-to-digital (A/D) converter synchronized by a frequency coherent 40 MHz pulse to obtain four evenly spaced samples A1,B1,A2 and B2 of each cycle of the signal, and means for adding, or subtracting, each sample to, or from, one of four accumulators to form the sums: ##EQU1## where M1 = 10 MHz Reference .multidot. Receiver Code .angle.0.degree.M2 = 10 mhz Reference .multidot. Receiver Code .angle.90.degree.The correlation functions that are used for the range measurements are then computed from the following equations:I = S1.sub.I cos .alpha. - S2.sub.I sin .alpha.Q = S1.sub.Q cos .alpha. - S2.sub.Q sin .alpha.where sin .alpha. and cos .alpha.